More than 300 state lawmakers hailing from all 50 states have added their voices to the chorus objecting to President Trump’s nomination of Betsy DeVos as education secretary.

The lawmakers, who are overwhelmingly Democrats, voiced their opposition to DeVos in a joint letter that is expected to be delivered to U.S. Senators on Monday, the day before a Senate committee is scheduled to vote on her nomination.

They comprise a minority of the more than 7,300 state legislators nationwide, but their criticisms echo those that have been made in recent weeks by Democratic Senators, labor unions, civil rights groups and advocates for children with disabilities, as well as many parents and teachers.

The state lawmakers argue that DeVos, who has no professional experience in education, is unqualified for the job and that the charter schools and voucher programs she has worked to create and expand have undermined public schools, which they see as critical civic institutions that serve the majority of students.

As states embrace greater authority over education under the new Every Student Succeeds Act, the legislators wrote, “we are deeply concerned that Ms. DeVos will bring her lack of experience with public education, her failure to understand key federal laws, and her track record of undermining public education at the state level with her to Washington.”

The letter was coordinated by SiX Action, a group that has ties to labor and pushes progressive policies within states. (Read the full letter at the bottom of this post.)

The state lawmakers’ letter is just one of the latest volleys in what has become a pitched partisan battle over DeVos’s confirmation.

America Rising Squared — an arm of the Republican super PAC America Rising — on Monday launched an online advertising campaign defending DeVos as someone who “knows what it takes to repair our failing schools.”

The 30-second video accuses Democrats of bowing to the will of teachers unions and “playing politics as usual” with DeVos’s nomination. It will run on social-media platforms nationally but will target residents of five states with Democratic senators: West Virginia, Montana, North Dakota, Missouri and Indiana.

“By trying to block this extremely well-qualified nominee, Senate Democrats are once again putting the interests of their big labor allies ahead of the needs of millions of American kids trapped in the failing status quo,” said Brian Rogers, executive director of America Rising Squared. “Betsy DeVos is a critical part of the change America voted for this election, and we look forward to her serving with great distinction as Secretary of Education.”

America Rising Squared has been involved in promoting other Cabinet nominees, including Jeff Sessions for attorney general, Scott Pruitt for administrator of the Environmental Protection Agency, Andrew Puzder for labor secretary, and Tom Price for health and human services secretary. But a spokesman said the five-figure ad buy on DeVos’s behalf is the organization’s “most significant involvement to date.”

The Senate Committee on Health, Education, Labor and Pensions is scheduled to vote on DeVos’s nomination Tuesday, with a full Senate vote expected in the coming weeks.

Sen. Al Franken (D-Minn.) said last week on MSNBC’s “Rachel Maddow Show” that virtually all Democrats will vote against DeVos’s nomination. But DeVos appears very likely to be confirmed: Republicans hold the Senate majority, and no GOP senators have indicated they intend to oppose her.